A nonprofit group is giving some farmers a financial hand so they can help bird species that are in steep decline.

The Vermont Fish and Wildlife Department asked landowners to put off cutting hayfields and pastures until August because of a drop in the populations of species that rely on grasslands for nesting.

John Buck, who holds the recently created position of avian biologist with the department, said the drop in numbers of many Vermont grassland birds has been precipitous in recent decades.

“For bobolink, it’s been a steady decline,” Buck said. “You could say they are in somewhere in the neighborhood of 25 percent of what they were 50 years ago. And others are greater than that — you know the loss is greater.”

The primary reason for the decline in these population has been habitat destruction caused by humans, Buck said.

But mowing later is not a casual proposition for all Vermonters. Buck acknowledged that farmers can face substantial feed and forage costs if they hold off on haying until August.

“I think every farmer would mow according to bobolink nesting schedule if they could, but they’re just in a really tough place,” Buck said. “The agricultural practices have become far more intensive than they were 40 or 50 years ago,” so in order for “farms to be competitive and stay in business, they don’t have a lot of choice.”

That’s where the Bobolink Project steps in. The nonprofit conservation group provides grants to farmers for leaving hay in the field longer as nesting habitat.

The organization is run by the Audubon societies of Massachusetts and Vermont, the University of Vermont and several other organizations. It works with farmers to identify which parts of their grasslands are most essential to conserve, then makes grants to offset the costs of buying whatever those acres would have produced.

This summer, the Bobolink Project provided subsidies to 17 farmers around New England to delay mowing on 600 acres of nesting habitat. The funding comes from donations.

All of Vermont’s grassland birds are migratory and fly far south for the winter, Buck said, so the health of their populations is also influenced by conditions in their southern habitats. But they hatch their young in Vermont and other parts of the northern U.S. during the summer.

A long history of change

The decline of grassland birds has not been caused exclusively by an increase in the frequency and intensity of mowing, Buck said. Long-term historical trends have played an important role.

Five or six hundred years ago, Buck said, the populations of grassland birds were intimately connected with the beaver population.

Before beavers were trapped nearly to extinction by colonists, the areas the animals periodically flooded probably “covered hundreds of acres in places that we wouldn’t even imagine,” Buck said.

At their peak, the domain influenced by New England beavers included the mouths of major rivers, all along the Connecticut River and really “any flat area at all, like all up and down Chittenden County,” Buck said.

Their populations went through boom and bust cycles. During a low population point, the beaver marshes would dry out into large meadows of grass and sedge — a key part of grassland bird habitat.

After humans largely eliminated the beaver, settlers created new grasslands in the form of pastures and fields. Indeed, the current consensus is that New England’s grassland bird population peaked during the 19th century when farms covered most of the arable land.

Since then, Buck said, the populations of Vermont’s grassland birds have declined partly because of land development, but more significantly because of changes in the economics of farming.

Over the 20th century, the total acreage of Vermont farmland fell greatly. Many former pastures and fields were reclaimed by forests, and the ones that remain see more intensive mowing, Buck said.